feat: frontend remote relay, kiosk hardening, CSS compositor fix

Frontend:
- Add remote-relay.ts: receives companion input via /ws/remote-relay,
  dispatches keyboard/mouse/scroll events into browser DOM
- Add CompanionIndicator.vue: NES gamepad icon when companion connected
- Wire relay start/stop to auth state in App.vue

Kiosk:
- Move Chromium data dir to /var/lib/archipelago/chromium-kiosk (encrypted)
- Disable MetricsReporting, AutofillServerCommunication, PasswordManager
- Remove --metrics-recording-only (contradicts disable-metrics)

CSS:
- Fix Chromium ghost rectangles: only apply preserve-3d + backface-visibility
  during transitions, not always-on (causes Chromium to skip painting
  off-viewport cards)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

image-recipe/build-auto-installer-iso.sh

@@ -2247,7 +2247,7 @@ while true; do
         --disable-background-networking \
         --disable-background-timer-throttling \
         --disable-backgrounding-occluded-windows \
-        --user-data-dir=/home/archipelago/.config/chromium-kiosk
+        --user-data-dir=/var/lib/archipelago/chromium-kiosk
     sleep 3
 done